As an example of a conventional dual polarization dipole antenna, the dual polarization dipole antenna disclosed in Korean Unexamined Patent Publication No. 2001-0040623 transmits polarized electrical radiation at an angle of +45° or −45° in relation to a predetermined arrangement of dipoles. The ends of the symmetrical or approximately symmetrical lines, which lead to respective dipole halves, are interconnected in such a way that the corresponding line halves of adjacent dipole halves, which are perpendicular to each other, are electrically connected, and the supply of electrical power to the diametrically opposite dipole halves results in a first polarization, and decouples a second polarization which is orthogonal thereto.
However, the conventional technology has a structure in which four dipoles are uniformly separated from each other, so that there is a problem in that the structure of the antenna is complicated.
Furthermore, the four uniformly-separated dipoles and two pairs of symmetrical feeding portions are made of a metal material and are coupled to each other on a radiation substrate, so there are problems, not only in that impedance matching is difficult to achieve, but also in that the broadband characteristic and the antenna gain are lowered.